package app

import (
	"context"
	"flag"
	"fmt"
	"io"

	"gitea.maximumdirect.net/eric/narratio/internal/config"
)

// Run executes the pipeline plan and persists manifest state.
func Run(ctx context.Context, args []string, out io.Writer) error {
	fs := flag.NewFlagSet("run", flag.ContinueOnError)
	fs.SetOutput(io.Discard)

	var pipelinePath string
	var sessionPath string
	var force bool
	fs.StringVar(&pipelinePath, "config", "", "path to pipeline.yml (optional; defaults searched)")
	fs.StringVar(&sessionPath, "session", "", "path to session.yml")
	fs.BoolVar(&force, "force", false, "force stage execution (reserved for future behavior)")

	if err := fs.Parse(args); err != nil {
		return fmt.Errorf("run: invalid flags: %w", err)
	}
	if fs.NArg() != 0 {
		return fmt.Errorf("run: unexpected positional arguments")
	}
	if sessionPath == "" {
		return fmt.Errorf("run: --session is required")
	}

	resolvedPipelinePath, err := resolvePipelineConfigPath(pipelinePath)
	if err != nil {
		return fmt.Errorf("run: %w", err)
	}

	cfg, err := config.Load(resolvedPipelinePath, sessionPath)
	if err != nil {
		return fmt.Errorf("run: %w", err)
	}
	if err := config.Validate(cfg); err != nil {
		return fmt.Errorf("run: %w", err)
	}

	stages := BuildFullPlan()
	summary, err := executeStages(ctx, cfg, stages, RunOptions{Force: force})
	if err != nil {
		return fmt.Errorf("run: %w", err)
	}

	_, err = fmt.Fprintf(
		out,
		"narratio run: session %s; executed=%d skipped=%d; manifest=%s\n",
		summary.SessionID,
		len(summary.Executed),
		len(summary.Skipped),
		summary.ManifestPath,
	)
	return err
}